Due to advances in molecular biology, the pathologenesis of many diseases can be elucidated at the gene level. This makes it possible to provide accurate diagnosis and effective treatment of such diseases. In fact, the treatment of many diseases, such as cardiovascular diseases, cerebral diseases, tumor, diabetes, AIDS, and gene therapy is attracting more and more attention. For example, if an anti-thrombogenic gene is delivered and localized to a specific artery, highly efficient gene transfer to the vascular cells and transgene expression at the target site will occur, effecting suppression of thrombosis. However, a key problem of localized delivery of exogenous genes within the body, so far, has not been solved. Simons et al. employed Pluronic F127 gel as a vehicle for gene delivery and localization (1992, Nature 359(3):67-70). A gene was added to a gel and then delivered to the carotid artery of an animal. A shortcoming of this method is that the gel is susceptible to being flushed from the target site by blood flow. Therefore, localized delivery of the gene cannot be effectively achieved. With respect to coated substrates, although several methods have been disclosed, the objective of those inventions is to have hydrophilic coatings lubricate the articles when they a:re in contact with an aqueous-based medium, such as a body fluid. The lubricous surface can decrease injury to macous membranes and other body tissue caused by the presence of the articles. U.S. Pat. No. 4,373,009 discloses a hydrophilic coating. The disclosed coating material is vinyl pyrrolidone copolymer containing active hydrogen. Another hydrophilic coating is made from polyacrylates. This coating is described by You-link Fan in U.S. Pat. No. 5,091,205. These types of coatings can exhibit low coefficient of friction when in contact with aqueous-based medium. But they are not fit for local delivery of genes because they do not absorb genes strongly enough. In addition, these polymers have unknown quality with respect to biocompatibility, purity, and toxicity. Thus, there remains a distinct need for a vehicle that can absorb genes strongly, and thereby locally deliver genes.